Duct fan in the form of a centrifugal fan

ABSTRACT

A duct fan (1) has a centrifugal fan with a motor (10) and a centrifugal impeller (11). A housing has an intake shell (2) on an intake side, that defines an intake portion (52), and accommodates the centrifugal impeller (11). The housing also has an exhaust shell (3) on an exhaust side that defines an exhaust portion (53). A bowl-shaped motor mount (5) is arranged in the exhaust shell (3). A continuous flow channel (20) to the exhaust portion (53) is formed between the motor mount (5) and the exhaust shell (3). A flow (S) generated by the centrifugal impeller (11), during operation, is guided by the flow channel (20).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 371 U.S. National Phase of InternationalApplication No. PCT/EP2021/065771, filed Jun. 11, 2021, which claimspriority to German Application No. 10 2020 119 881.7, filed Jul. 28,2020. The entire disclosures of the above applications are incorporatedherein by reference.

DESCRIPTION

The disclosure relates to a duct fan, particularly a centrifugal fan,with a motor and a centrifugal impeller.

Duct fans are used within a duct arrangement to create an air flowthrough the duct arrangement with a predetermined duct diameter. Onecategory of these fans is the so-called in-line duct fans. Here themaximum housing diameter of the duct fan corresponds to that of the ductdiameter of the duct arrangement. Axial fans and diagonal fans, inparticular, are used for this application. Their advantage lies in theircompact design with good flow guidance. However, they do not attain thepressure and efficiency of a centrifugal fan. This is why axial fans anddiagonal fans are used for high volume flows at low pressures.

When using a centrifugal fan that sucks air in axially and blows it outradially in order to achieve higher pressures, the housing diameter ofthe housing accommodating the centrifugal fan is always substantiallylarger than the duct diameter of the duct arrangement. An in-linevariant therefore cannot be implemented with centrifugal fans.

The disclosure is aimed expressly at a duct fan, particularly acentrifugal fan. It is known in the prior art to construct the housingin multiple parts and to integrate the motor mount, for the motor of thecentrifugal fan, into the housing part on the exhaust side. Thecentrifugal impeller of the centrifugal fan promotes a volume flow thatis blown unaffected into the exhaust-side housing part and then into theadjacent duct arrangement. This results in recirculation zones andseparation of the flow in the exhaust-side part of the housing. This hasa negative effect both in terms of efficiency and noise.

SUMMARY

It is therefore an object of the disclosure to provide a duct fan, acentrifugal fan, whose flow guidance is improved to increase itsefficiency while simultaneously reducing noise.

This object is achieved by the combination of a duct fan with acentrifugal fan, a motor and a centrifugal impeller, a housing with anintake shell on an intake side defining an intake portion. The intakeshell accommodates the centrifugal impeller. An exhaust shell, on anexhaust side, defines an exhaust portion. A bowl-shaped motor mount,fixedly receiving the motor, is arranged in the exhaust shell. Acontinuous flow channel, to the exhaust portion, is formed between themotor mount and the exhaust shell. A flow (S), generated by thecentrifugal impeller during operation, is guided through the flowchannel.

A duct fan, particularly a centrifugal fan, with a motor and acentrifugal impeller, has a housing with an intake shell on the intakeside. The intake shell defines an intake portion and accommodates thecentrifugal impeller. An exhaust shell is on the exhaust side anddefines an exhaust portion. A bowl-shaped motor mount securely holds themotor in the exhaust shell. A continuous flow channel to the exhaustportion is formed between the motor mount and the exhaust shell. Thus, agenerated flow of the centrifugal impeller, during operation, is guidedthrough the exhaust shell.

As in the prior art, the duct fan housing is attached to the adjacentduct arrangement through which the flow travels. The intake shell andexhaust shell determine the enlarged diameter relative to the ductarrangement. As viewed in the direction of flow, the bowl shape of theintake shell and exhaust shell, respectively, provides fora widening toan enlarged diameter and the subsequent narrowing with the reduction ofthe diameter to the duct arrangement. The motor mount in the exhaustshell is at least partially bowl-shaped to create the flow channel forthe flow that is generated by the centrifugal fan. Thus, this definesthe flow guidance from the centrifugal impeller to the exhaust portion,which minimizes recirculation zones and flow separations. This has apositive effect on efficiency and reduces noise.

One advantageous refinement of the duct fan includes a plurality ofdownstream guide vanes, distributed in the circumferential direction,arranged in the flow channel. The downstream guide vanes are radialvanes with guide surfaces for the flow that extend through the flowchannel.

One advantageous embodiment of the duct fan includes the downstreamguide vanes extending from an outer lateral surface of the motor mountto an inner wall surface of the exhaust shell. The guide vanes subdividethe flow channel into a plurality of individual channels in thecircumferential direction. Due to the radial extension of the downstreamguide vanes from wall to wall, the individual channels are closed andonly merge again with one another in the exhaust portion.

In one preferred design variant, the downstream guide vanes areintegrally formed on the motor mount. This reduces the number of partsand the effort required to assemble the motor mount on the outer shell.

In the prior art, the motor mount could often be integrally formed withthe exhaust shell. In the present duct fan, however, the motor mount isa separate part. Nevertheless, for one advantageous and simple assemblyoption, receiving grooves are provided on the exhaust shell for securedinsertion of fastening webs formed on the motor mount. The motor mountcan thus be fixed in position in the exhaust shell while beingdetachably fastened at the same time. The receiving grooves arepreferably formed in a tubular end portion of the exhaust shell thatdefines the exhaust portion. The receiving grooves have practically noeffect on the flow in this region.

In one design variant of the duct fan, the fastening webs on the motormount are formed by the downstream guide vanes. Thus, the downstreamguide vanes assume both the function of guiding the flow through theflow channel and fastening the motor mount to the exhaust shell.

The flow channel between the exhaust shell and the motor mount isensured by their two bowl-shaped wall portions. The motor mountcomprises a shell with a cross section that tapers in the flowdirection. The taper substantially corresponds to the outer shell. Thus,the flow channel has a substantially constant flow width. However, thedownstream guide vanes preferably extend in the axial flow directionbeyond the shell of the motor mount that forms the flow channel,particularly into the exhaust portion. Thus, this guides the flow intothe adjacent duct arrangement.

In one advantageous embodiment, the shell of the motor mount, that formsthe flow channel, has, on the axial side facing toward centrifugalimpeller, an axial projection that extends around in the circumferentialdirection. The axial projection defines an intake portion of the flowchannel and protrudes axially in the direction of the centrifugalimpeller relative to the downstream guide vanes. In other words, thedownstream guide vanes begin their extension in the flow channel at anaxial distance from an axial outer edge of the shell of the motor mount.

In one aerodynamically favorable embodiment of the duct fan, it includesthe downstream guide vanes curved in some portions in thecircumferential direction. A profile that is curved in an arc shape isespecially preferred. The curved profile is provided particularly in theregion of the motor mount where the shell is located. In the adjoiningportion, the downstream guide vanes end so as to extend in the axialflow direction, parallel to the axis of rotation of the centrifugal fan.

The noise reduction of the duct fan is positively reinforced by onerefinement where a wall portion of the motor mount shell that forms theflow channel, is perforated with through holes. Noise-reducinginsulation material can then be introduced into the shell. In onefavorable embodiment, the shell of the motor mount has an axiallycentered motor base for mounting the motor. It defines a receiving spacebetween an inner wall surface of the perforated wall portion and themotor base. This receiving space can be used in the same manner for thearrangement of noise-reducing insulation material.

A refinement for noise reduction of the duct fan, particularly in theregion of the outer shell, is also provided. For this purpose, theexhaust shell has a respective radial widening in the region of the flowchannel between the downstream guide vanes, as viewed in thecircumferential direction, designed to accommodate noise-reducinginsulation material. In an axial top view, a kind of flower shaperesults from the widenings of the exhaust shell distributed in thecircumferential direction. The radial widenings follow the extensionbetween two respective downstream guide vanes. Preferably they are alsocurved or twisted in an arc shape in the circumferential direction. Thenoise-reducing insulation material is preferably injected directly intothe radial widenings on the exhaust shell. Insulating foam can be usedas the insulation material, for example.

For advantageous inflow into the flow channel of the air flow generatedby the centrifugal impeller, the duct fan has a maximum outside diameterof the shell of the motor mount on the intake side larger than anoutside diameter of the centrifugal impeller. Furthermore, an embodimentis favorable where the intake portion defines an intake nozzle thatextends in the axial flow direction into an intake opening of thecentrifugal impeller.

In the case of the duct fan, one advantageous refinement includes theintake shell and the exhaust shell secured to one another by a fasteningdevice when the shells are placed on top of one another. In so doing,they establish a position of the motor mount in the exhaust shell.Clamps or a bayonet joint, for example, can be used as a fasteningdevice. In particular, the motor mount is positioned between the intakeshell and the exhaust shell and is also fixed in place when they aresecured together.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantageous refinements of the disclosure are included in thesubclaims and/or depicted in greater detail below together with thedescription of the preferred embodiment of the invention with referenceto the drawing. In the drawing:

FIG. 1 Is a cross-section view of a design variant of the duct fan.

DETAILED DESCRIPTION

FIG. 1 shows a cutaway view of a duct fan 1 in the form of a centrifugalfan. The duct fan 1 includes two housing parts that are embodied as anintake shell 2, on the intake side, and an exhaust shell 3, on theexhaust side. The intake shell 2 has a tubular intake portion 52 and theexhaust shell 3 has a tubular exhaust portion 53. The tubular portions52, 53 attaches the duct fan 1 on the intake side and exhaust side,respectively, to an external duct arrangement. The flow diameter of theintake shell 2 and of the exhaust shell 3 is also substantially largerfor the centrifugal fan due to the design. The centrifugal fan isarranged with its motor 10 and its centrifugal impeller 11, driven bythe motor 10, in the intake shell 2. The centrifugal impeller 11includes a cover disc, a base disc, and impeller blades extendingtherebetween. During operation, the centrifugal impeller 11 draws in aflow S axially through the intake portion 52 and blows it out radiallyin the direction of the inner wall surface of the intake shell 2.

The motor 10 is attached to the axially centered motor base 22 of thebowl-shaped motor mount 5, which, in turn, is accommodated and securedin the exhaust shell 3. The bowl-shaped motor mount 5 includes a shell6. The axially centered motor base 22 is integrally formed on the shell6. The downstream guide vanes 4 are also preferably integrally formed onthe outside of the shell 6 in the circumferential direction. Thecontinuous flow channel 20, to the exhaust portion 53, is formed betweenthe shell 6 of the motor mount 5 and the exhaust shell 3. A flow S isgenerated by the centrifugal impeller 11, during operation, and isguided by the flow channel 20. The flow channel 20 is divided intomultiple individual channels by the downstream guide vanes 4. This isdue to the downstream guide vanes 4 extending continuously from theouter surface of the shell 6 of the motor mount 5 to the inner wallsurface of the exhaust shell 3. The individual channels are thencombined again in the downstream region of the shell 6 to form a flowchannel. The downstream guide vanes 4 extend in the axial flow directionbeyond the shell 6 of the motor mount 5 that forms the flow channel 20and into the tubular exhaust portion 53. On the axial side facing towardthe centrifugal impeller 11, the downstream guide vanes 4 are spacedapart from the axial edge of the shell 6 via the axial projection 12.The axial projection 12 runs parallel to the axis of rotation of thecentrifugal fan 11. The inflow into the flow channel 20 is thereforeinitially defined only by the shell 6 and the exhaust shell 3. It isonly within the region of the flow channel 20 where the shell 6 beginsto reduce in cross section that the flow is guided via the downstreamguide vanes 4. The maximum outer diameter of the shell 6 of the motormount 5 on the intake side is larger than the outer diameter of thecentrifugal impeller 11.

The downstream guide vanes 4 are curved in some portions in thecircumferential direction for this purpose. The preferably arcuatecurvature 63 is especially advantageous, but other constant curvatures,including an S-shaped profile, can also be provided as required. Thedirection of curvature is preferably coordinated with the direction ofrotation of the centrifugal fan 11. The downstream guide vanes 4 end inthe exhaust portion 53, extending parallel to the axial flow direction.The flow S is guided by the downstream guide vanes 4 through the flowchannel 20 along the shell 6 of the motor mount 5 and exhaust shell 3.

A plurality of receiving grooves 9 are formed in the exhaust portion 53for fixedly receiving the downstream guide vanes 4. The downstream guidevanes 4 are inserted into the receiving grooves 9 in order to mount themotor mount 5 in the exhaust shell 3. This secures the motor mount 5 inthe exhaust shell 3. Alternatively, a solution is also included, albeitnot shown, where fastening webs are arranged or formed on the motormount 5 independently of the downstream guide vanes 4 and secure themotor mount 5 in the receiving grooves 9 of the exhaust shell 3. Theintake shell 2 and the exhaust shell 3 are placed one on top of theother and secured to one another by clamps 51. The motor mount 5 ispositioned with a portion of the downstream guide vanes 4 between thehousing parts of the intake shell 2 and exhaust shell 3 and also securedthrough the securement thereof and fixed in position. In particular, itis ensured that when the clamps 51 are fastened, the downstream guidevanes 4 are pushed completely into the receiving grooves 9.

A wall portion of the shell 6 of the motor mount 5 has a plurality ofthrough holes 8 that form a perforation. The size of the through holes 8decreases as viewed in the direction of flow. Noise-reducing insulationmaterial (not shown) is introduced into the receiving space 15 betweenthe shell 6 of the motor mount 5 and the motor base 22 in order tominimize the noise that is generated by the flow along the shell 6. Theperforation in the form of the through holes 8 increases the effect ofthe noise-reducing insulation material. In addition, radial widenings 7are formed on the exhaust shell 3 in the regions between the downstreamguide vanes 4 whose course in the circumferential direction and in theaxial direction corresponds to that of the downstream guide vanes 4.Noise-reducing insulation material (at reference number 77, but notshown) is also introduced, preferably injection-molded, into thewidenings 7. A reduction in noise is thus achieved on the exhaust shell3 as well.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

1-15. (canceled)
 16. A duct fan comprising: a centrifugal fan with amotor and a centrifugal impeller; a housing includes an intake shell onan intake side defining an intake portion, the intake shell accommodatesthe centrifugal impeller; an exhaust shell on an exhaust side defines anexhaust portion: a bowl-shaped motor mount, for fixedly receiving themotor, is arranged in the exhaust shell, and a continuous flow channel,to the exhaust portion, is formed between the motor mount and theexhaust shell and a flow (S) generated by the centrifugal impellerduring operation, is guided through the flow channel.
 17. The duct fanas set forth in claim 16, further comprising a plurality of downstreamguide vanes, distributed in a circumferential direction, are arranged inthe flow channel.
 18. The duct fan as set forth in claim 17, wherein thedownstream guide vanes extend from an outer lateral surface of the motormount to an inner wall surface of the exhaust shell and subdivide theflow channel into a plurality of individual channels in thecircumferential direction.
 19. The duct fan as set forth in claim 16,wherein the downstream guide vanes are integrally formed on the motormount.
 20. The duct fan as set forth in claim 16, further comprisingreceiving grooves on the exhaust shell for secured insertion offastening webs formed on the motor mount.
 21. The duct fan as set forthin claim 20, wherein the receiving grooves are formed in a tubular endportion of the exhaust shell defining the exhaust portion.
 22. The ductfan as set forth in claim 20, wherein the fastening webs are formed bydownstream guide vanes.
 23. The duct fan as set forth in claim 17,wherein the plurality of downstream guide vanes extend in an axial flowdirection beyond a shell of the motor mount that forms the flow channel.24. The duct fan as set forth in claim 23, wherein the shell of themotor mount that forms the flow channel has an axial projection thatextends around in the circumferential direction, defines an intakeportion of the flow channel, and protrudes axially in the direction ofthe centrifugal impeller relative to the downstream guide vanes.
 25. Theduct fan as set forth in claim 17, wherein the plurality of downstreamguide vanes are curved in some portions in the circumferentialdirection, particularly in an arc shape, and end so as to extend axiallyin the axial flow direction.
 26. The duct fan as set forth in claim 16,further comprising a wall portion of a shell that forms the flow channelof the motor mount is perforated with through holes.
 27. The duct fan asset forth in claim 26, wherein the shell of the motor mount has anaxially centered motor base for mounting the motor and defines areceiving space between an inner wall surface of the perforated wallportion of the shell and the motor base for the arrangement ofnoise-reducing insulation material.
 28. The duct fan as set forth inclaim 17, wherein the exhaust shell has a respective radial widening inthe region of the flow channel between the plurality of downstream guidevanes as viewed in the circumferential direction for accommodatingnoise-reducing insulation material.
 29. The duct fan as set forth inclaim 16, wherein the intake shell and the exhaust shell can be securedto one another by a fastening device when placed on top of one anotherand, in so doing, establish a position of the motor mount in the exhaustshell.
 30. The duct fan as set forth in claim 16, wherein a maximumoutside diameter of a shell of the motor mount on the intake side islarger than an outside diameter of the centrifugal impeller.